ELECTROPHYSIOLOGICAL PROPERTIES AND GLUCOSE RESPONSIVENESS OF GUINEA-PIG VENTROMEDIAL HYPOTHALAMIC NEURONS INVITRO
ELECTROPHYSIOLOGICAL PROPERTIES AND GLUCOSE RESPONSIVENESS OF GUINEA-PIG VENTROMEDIAL HYPOTHALAMIC NEURONS INVITRO
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DOI：
10.1113/jphysiol.1986.sp016276
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发表时间：
1986-11-01
影响因子：
5.5
通讯作者：
SUGIMORI, M
中科院分区：
文献类型：
--
作者：
MINAMI, T;OOMURA, Y;SUGIMORI, M
The membrane properties of neurons in the guinea-pig ventromedial hypothalamic nucleus (v.m.h.) were studied in vitro brain slice preparations The average resting potential was -62.9 .+-. 5.4 mV (mean .+-. S.D.), input resistance was 155 .+-. 58 M.OMEGA. and action potential amplitude was 69.9 .+-. 6.3 mV. Three types of neurone were identified. The type A neurons were characterized by a short membrane time constant (7.3 .+-. 2.0 ms) and a small after-hyperpolarization (a.h.p.) (2.0 .+-. 1.2 mV) with a short half decay time of 67 .+-. 55 ms after stimulation with a long outward current pulse. Type B had a long time constant (18.8 .+-. 5.7 ms) and a large a.h.p. (6.9 .+-. 2.4 mV) with a medium half decay time of 203 .+-. 90 ms. Type C was characterized by a long time constant (14.3 .+-. 2.3 ms) and a large a.h.p. (6.5 .+-. 1.5 mV) with a long half decay time of 478 .+-. 230 ms. The slopes of the frequency-current (f-I) plots of the three types were different, particularly for the first spike interval. The slopes for the type A (414 .+-. 102 impulses s-1 nA-1) and type B neurons (480 .+-. 120 impulses s-1 nA-1) were steeper than that for the type C neurons (178 .+-. 41 impulses s-1 nA-1). This difference is probably related to the relatively long first interval observed in the type C neurons. In all type B and a few type C neurons, when the membrane potential was hyperpolarized beyond-65 mV the application of orthodromic or direct stimulation generated a burst of spikes, consisting of a low-threshold response (l.t.r.) of low amplitude and superimposed high-frequency spikes. At the original resting potential, outward current pulses produced a train of low-frequency spikes. In type C neurons maintained in a depolarized state (about -50 mV), inward current pulses produced a specific delay of the return to the original membrane potential. This delayed return was thought to be generated by activation of a transient K+ (IA) conductance. Stimulation at the lateral edge of the v.m.h. produced excitatory post-synaptic potentials (e.p.s.p.s.) in type A neurons, e.p.s.p.s. with l.t.r. in type B neurons and e.p.s.p.-inhibitory post-synaptic potential sequences in type C neurons. About 20% of v.m.h. neurons, particularly the type C cells, were depolarized by glucose application with an associated increase in the input membrane resistance. The mean reversal potential for the depolarization was -89.2 .+-. 2.0 mV, indicating a decrease in K+ conductance. Horseradish peroxidase (HRP) injection after examination of the membrane properties revealed three types of neurone which were related morphologically, with good correlation to the A, B and C classification. From these results, it can be concluded that there is electrophysical heterogeneity associated with anatomical differences in neurons in the v.m.h. Based on these differences, the neurons were classed into types A, B and C, with the type B neurons showing l.t.r. and the type C having IA current and glucose responsiveness.
